The present invention relates generally to the field of bearing assemblies. More particularly, the invention relates to a novel system for mounting and interfacing a plain or sleeve bearing assembly on a shaft or other mechanical component.
In the field of bearings, a wide variety of structures and techniques are known and are commonly in use. Such assemblies include both plain or sleeve bearings, and bearings incorporating bearing elements, such as rollers, balls, and so forth. In the former type, two bearing elements are brought together and rotate with respect to one another without separate bearing elements interposed therebetween. Such bearings are common in a number of applications, typically where loads are somewhat reduced as compared to applications for roller or ball bearings.
In sleeve bearing assemblies of certain known types, a bearing assembly is supported within a housing. The housings may be of any conventional style, such as pillow block styles, two and four bolt flange styles, and so forth. The bearing assembly includes an inner housing and an inner sleeve. The inner sleeve is snapped or press fit within the inner housing. In certain models, the inner sleeve may be made of a non-metallic material, such as a polymer, graphite, carbon, and so forth. A rotating member is supported within the inner sleeve and the interface between the inner sleeve and the rotating member constitutes the bearing interface of the assembly.
In conventional applications for sleeve bearings of the type described above, a shaft, hub, or similar rotating element is slid within the inner sleeve during installation, and rotates directly within the inner sleeve during use. A lubricating medium may be provided at the interface, or the qualities of the inner sleeve itself may provide sufficient friction reducing properties.
While bearing assemblies of the type described above are sufficient in many applications, there are not without drawbacks. For example, where an inner sleeve of a sleeve bearing assembly is interfaced directly with a shaft or other rotating element, chaffing, wear and similar degradation can occur both to the inner sleeve and to the rotating member. Such degradation is particularly troubling on shafts of machinery, due to the eventual need to disassemble the machinery and replace the shaft when the degradation becomes sufficiently advanced. In many applications, the degradation may be caused by walking, fretting or other marring of the shaft due to the direct contact with the inner sleeve of the bearing assembly.
Another problem with sleeve-type bearings has been their inability to withstand thrust loading. Depending upon the bearing configuration and its materials of construction, such thrust loading may need to be avoided completely or substantially limited due to the potential for deforming the bearing elements or rapidly degrading the bearing integrity. This is particularly the case where the inner sleeve of the bearing assembly is made of a non-metallic substance, such as a polymer.
There is a need, therefore, for an improved bearing system capable of avoiding wear to a supported and rotating member, and able to withstand higher degrees of thrust loading. There is a particular need for an improved bearing system which is simple to install and which can be based upon existing styles and configurations of bearings and bearing housings.
The present invention provides an improved bearing system designed to respond to such needs. The system is particularly well-suited to a plain or sleeve bearing assemblies. The system may be adapted for sleeve bearings having a variety of construction materials including graphite, carbon, babbitt, bronze, and other metals, and is particularly well-suited to bearing assemblies employing a polymeric inner sleeve. The system may be employed with a variety of rotating elements, including shafts, hubs, rollers, and so forth. It should be noted that while in the present description references is made to a rotating element supported within the bearing, the present system may be used in situations where a central element, such as a shaft, supports a rotating element disposed about it, such as roller, pulley, or the like.
The present technique is based upon the use of an inner ring designed to interface between an inner sleeve of a bearing assembly and a central machine element. Again, the central machine element may typically be a rotating shaft. The inner sleeve and inner ring define a bearing interface therebetween. The inner ring preferably includes a series of longitudinal slots or slits such that radial contraction of the inner ring is available during installation. A collar is fitted to the inner ring and secures the inner ring to the central element or shaft. The bearing assembly may be of any suitable design and style, including plain or sleeve bearings having polymeric inner sleeves. In a present design, the bearing assembly includes an inner sleeve and an inner housing which are press fit to one another. The inner housing may be mounted within a conventional bearing housing, such as a housing having a spherical support surface allowing for some axial misalignment of the rotating element.
The provision of the bearing interface between the inner ring and the inner sleeve of the sleeve bearing affords localization of any wear at the inner ring or the inner sleeve. Thus, fretting, marring, and other degradation of the shaft are avoided. Moreover, the collar, in conjunction with a thrust extension of the inner sleeve provides for thrust loading of the bearing assembly. The overall assembly then affords both limitation of wear on a supported machine element, as well as the resistance to thrust loading.